Polyether defoamers are polymer-based antifoaming agents utilizing polyether compounds—formed through ring-opening polymerization of ethylene oxide and propylene oxide—as core active ingredients. Their unique molecular structure provides good hydrophilicity at room temperature for uniform dispersion in aqueous systems, while undergoing reversible phase transformation upon heating or mechanical shear, transitioning from dissolved state to finely dispersed particles that deliver exceptional defoaming and foam suppression performance. Particularly suitable for harsh environments including high temperatures and strong alkalinity, these defoamers offer outstanding dispersion stability and system compatibility without causing surface defects or affecting product transparency. Widely applied in bio-fermentation, textile dyeing, industrial cleaning, metalworking fluids, and papermaking aqueous systems, their highly efficient and persistent foam control capabilities coupled with environmentally friendly characteristics make them indispensable solutions for numerous industrial processes.